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HELP!!!

Discussion in '1982-Present GM Diesel' started by joez, Apr 25, 2004.

  1. joez

    joez 1/2 ton status

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    Ok, so i am changing injectors, i just changed out the ones that i knew were bad, bled the lines, started it, and it is knocking VERY BAD now. It is much worse than before. Only now it sounds like it is coming from the oil pan, like it is a rod knock that was masked by the bad injectors. I am trying to change them all but it is now raining and i dont have a garage. Any input on why it would be knocking so much worse now?
     
  2. BlueBlazer

    BlueBlazer 1/2 ton status

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    It may just be the normal 6.2 sound, but you aren't used to it since your injectors were bad.
     
  3. joez

    joez 1/2 ton status

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    I sure hope that this is not the normal sound, this thing is knocking like a like a swat team is trying to break out of the pan.
     
  4. BlueBlazer

    BlueBlazer 1/2 ton status

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    Hmm, is there air in the system still? Are the injectors the same spec as the old ones (same VOP, orifice size)?
     
  5. joez

    joez 1/2 ton status

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    Yes, injectors are the same spec. There wasnt any air in it, but i just cracked a line again and it was slightly foamy coming out, so, i guess ill now be tracing fuel lines.
     
  6. joez

    joez 1/2 ton status

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    Drove it today and it sounds like it is going to throw a rod through the pan. No air in the system anymore (checked twice today), so i am betting my rod bearings are shot.

    Looks like ill be tearing this one out as soon as i can find a decent 4bt.
     
  7. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    [ QUOTE ]
    Ok, so i am changing injectors, i just changed out the ones that i knew were bad, bled the lines, started it, and it is knocking VERY BAD now.

    [/ QUOTE ]

    So it wasn't knocking before you did this work?

    Fire it up and loosen off one injector at a time. If it is still knocking tighten that one back up and move to the next. I think you have a fubar injector...you don't develop rod knock by swapping injectors.

    Rene
     
  8. joez

    joez 1/2 ton status

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    It was knocking before, and when i would crack a line of a bad injector it would go away. So, i ordered up 8 rebuilt injectors (might as well do them all at once right?), and started swaping them out. Started on the drivers side rear, worked my way to the front of the motor. that side actually had 2 not so good injectors on it. At this point it started to rain, which they hadnt called for in the forcast. So i hurry up, pull the GP's, bleed the lines, put the GP's back in and start it up. First think i hear is KNOCK KNOCK KNOCK. Its coming from the pan. So i shut it down, and re-check the lines for air-nothing. Now later it did still blow a couple bubles out, but after being checked 3 times now for air, there is none. No bad/cracked fuel lines. I can crack loose each new injector line and the knock stays there.

    The next day i started swapping the other bank, got rained out again. Still knocking.

    I have a couple left that need to be done, i am hoping that it may be one of those, but i doubt it. My luck isnt that good.
     
  9. imiceman44

    imiceman44 1 ton status

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    Well your luck could be like mine.
    First diesel I bought had that knock and I figured maybe it's the injectors, turned out it was one bearing that disapeared.
    I buy another one, and this time it's very low compression.
    Good thing I buy them really cheap.
    /forums/images/graemlins/grin.gif

    By the way, it could be that your injectors weren't working good and now with better performance the rods are knocking harder so the noise is louder.
    /forums/images/graemlins/frown.gif

    [ QUOTE ]
    It was knocking before, and when i would crack a line of a bad injector it would go away. So, i ordered up 8 rebuilt injectors (might as well do them all at once right?), and started swaping them out. Started on the drivers side rear, worked my way to the front of the motor. that side actually had 2 not so good injectors on it. At this point it started to rain, which they hadnt called for in the forcast. So i hurry up, pull the GP's, bleed the lines, put the GP's back in and start it up. First think i hear is KNOCK KNOCK KNOCK. Its coming from the pan. So i shut it down, and re-check the lines for air-nothing. Now later it did still blow a couple bubles out, but after being checked 3 times now for air, there is none. No bad/cracked fuel lines. I can crack loose each new injector line and the knock stays there.

    The next day i started swapping the other bank, got rained out again. Still knocking.

    I have a couple left that need to be done, i am hoping that it may be one of those, but i doubt it. My luck isnt that good.

    [/ QUOTE ]
     
  10. joez

    joez 1/2 ton status

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    [ QUOTE ]
    By the way, it could be that your injectors weren't working good and now with better performance the rods are knocking harder so the noise is louder.

    [/ QUOTE ]

    Thats what im thinking it is. I tried to defend this motor to all my buddies and family, who all did not want me to get it. they knew it had a bad rap. I buy it anyway. What happens? Injection pump fails first, then the injectors, now its got a damn rod knock. Im either putting a cummins in it or a big block.
     
  11. arveetek

    arveetek 1/2 ton status

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    [ QUOTE ]
    I tried to defend this motor to all my buddies and family, who all did not want me to get it. they knew it had a bad rap. I buy it anyway. What happens? Injection pump fails first, then the injectors, now its got a damn rod knock. Im either putting a cummins in it or a big block.

    [/ QUOTE ]

    It's not a 6.2L design flaw or the 6.2L's fault that you have had such problems. It simply comes with buying a used vehicle. Installing a big block will cut your fuel mileage by at least in half (15 to 20 mpg down to 5 to 10 mpg), and swapping in a Cummins is hard and expensive. I'd just fix the 6.2L, myself. You could do a total 6.2L rebuild for less than the purchase price of a used Cummins. /forums/images/graemlins/whistling.gif

    Casey
     
  12. joez

    joez 1/2 ton status

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    Yes, I know its not the motors fault, but i know i will never hear the end of it. It was a border patrol truck down in NM for a few years, if that tells you anything. The body and frame were what i really bought it for, it is absolutly mint. Now after driving it for 7 months and one winter, the 10 bolts, and the exhaust tips have developed a little surface rust.

    I know a big block will cut mileage more than in half, but i drive the K5 on average 50 miles a week. And about the price of the cummins, come tuesday i may have two running 6bt's for dirt cheap. I just need to make sure that they are cummins motors, the guy i talked to only knew that they were inline diesels, i find out tuesday when i talk to the owner. I know a good majority of these were equiped with 6bt's, so this sounds promising.

    Or i could go the 6.5 TD route, it just depends on the mood i am in when i find one of the 3 for sale. Ive got more than a few Big Blocks that i can get my grubby hands on, only thing keeping me from doing that right now is that i would want to build that. Which gets expensive.

    For now i will just do rod bearings on the 6.2 and see what happens, if it goes away, then i have more time to find the motor i want. If it doesnt, well, that was money wasted. Who knows, i have heard of nasty knocks coming from bad precumbustion chambers, maybee i pull the heads and see what is going on in there.
     
  13. beater_k20

    beater_k20 Banned

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    if you're going through the trouble of putting rod bearings in it, dont half ass it. put new mains in it too, and make sure all the journals are within spec.
     
  14. joez

    joez 1/2 ton status

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    Dont worry, i plan on doing mains too. If ive already got it appart then why not. But im not going to invest in a new crank if thats shot.
     

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